class or entity relations - one relation, containing multiple class members (composed Keys)?

Question

How could I paint relations containing "composed keys", a relation between multiple columns in both classes? Something like

`Foo2::(column2,column3,column4) --> Foo1::(column2,column3,column4)`

I only know how to paint relations between individual class members, for example

```

@startuml
class Foo1 {
column1
column2
column3
column4
column5
column6
}

class Foo2 {
column1
column2
column3
column4
column5
column6
}

Foo2::column1 --> Foo1::column1
'Foo2::(column2,column3,column4) --> Foo1::(column2,column3,column4)
@enduml

```